NgxExport.Tools.System

Various functions to access low-level Nginx API

Various functions to access low-level Nginx API, mostly wrappers around corresponding functions and data from module NgxExport.

Exported functions

terminateWorkerProcess :: String -> IO a

Terminates the Nginx worker process from a Haskell service.

Nginx master process shall not spawn a new worker process thereafter. This function throws exception TerminateWorkerProcess, and therefore terminates the worker process effectively only from a Haskell service.

restartWorkerProcess :: String -> IO a

Restarts the Nginx worker process from a Haskell service.

Nginx master process shall spawn a new worker process after termination of the current one. This function throws exception RestartWorkerProcess, and therefore terminates the worker process effectively only from a Haskell service.

finalizeHTTPRequest :: Int -> Maybe String -> IO a

Finalizes the current HTTP request from a Haskell asynchronous variable handler.

This function throws exception FinalizeHTTPRequest, and therefore terminates the HTTP request effectively only from a Haskell asynchronous variable handler.

workerProcessIsExiting :: SomeException -> Bool

Checks that a generic exception is of type WorkerProcessIsExiting.

This can be useful to check quickly in an exception handler whether a Haskell service has been interrupted because the worker process is exiting.

ngxRequestPtr :: ByteString -> Ptr ()

Unmarshals the value of Nginx variable $_r_ptr into a pointer to the Nginx request object.

This is safe to use in request-based Haskell handlers such as synchronous and asynchronous tasks and content handlers, but not in services and their derivatives. In asynchronous tasks and content handlers the value must be used as read-only. The value can be passed into a C plugin, however, as opposed to usual functions in Nginx C code, it must be tested against the NULL value.

ngxNow :: IO CTime

Returns the current time as the number of seconds elapsed since the UNIX epoch.

The value is taken from Nginx core, so no additional system calls get involved. On the other hand, it means that this is only safe to use from an Nginx worker's main thread, i.e. in synchronous Haskell handlers and service hooks. Be also aware that this is a small type casting hack: the value is interpreted as being of type time_t while having been actually wrapped in a bigger C struct as its first element.

ngxPid :: IO CPid

Returns the PID of the current worker process cached in Nginx core.